I tested this as follows in Windows 10 with RBB2 build 165, and my finding was as follows.
(a) It did export correctly when one selected Bootstrap 4, with or without components.
(b) It did export correctly when one selected Bootstrap 3 without components.
(c) It did not export social icons when one selected Bootstrap 3 with components.

The problem at (c) was not found when using Bootstrap 3 in RSD2 build 2044